Compounded hydrocarbon products



Patented Dec. 4, 1945 COMPOUNDED HYDROCARBON PRODUCTS David W. Young,Roselle, N. 3., assignor to Standard Oil Development Company, a corpoflration of Delaware No Drawing. Application semis, 1943, Serial No.498,595

15 Claims.

I This invention relates to a new antioxidant additive for aliphatichydrocarbon products and especially to a class of additives which areespecially useful as detergent and anticorrosion agents for minerallubricating oils.

The new class of additives comprises the alkyl esters of p-hydroxydithiobenzoic acid and analogous compounds having other aryl nuclei andsalts of all such compounds. These compounds are very effectiveantioxidants for a wide variety of aliphatic hydrocarbon products, such,for example, as mineral lubricating oils, paraffin waxes, hydrocarbonpolymers, natural rubber, synthetic rubber and the like. The metallicsalts of these compounds have the further advantage of acting asdetergents and sludge dispersers when incorporation in crankcaselubricating oils. They are especially valuable for this purpose, sincethey do not have the disadvantage, common to many metal derivatives .oforganic compounds known to the art, of corroding alloy bearings, such asthe cadmium-silver and copperdead bearings now widely used in automotiveengines.

These salts have the further advantage of being substantiallynon-water-sensitive, that is, they do not tend to be removed from oilsolution when lubricating oils containing them come into contact withwater. Many metal-containing organic compounds, otherwise satisfactoryas detergent additives for use in internal combustion engine lubricants,do have this undesirable property of water sensitivity. Absence of thischaracteristic is of particular importance in marine service wherecontact with sea water very often occurs.

lit-is therefore one of the principal objects of the invention toprovide a new class of addition agents for. oils which are to be used ascrankcase lubricants for internal combustion engines which where Ar isan aromatic nucleus, which for illustration may be a benzene nucleus, 9.diphenyl nucleus, or a condensed ring nucleus, such as naphthalene,where T is hydrogen, a metal equivalent of hydrogen selected from groupsI, I1, I11, IV and VIII of the periodic table or a salt formingnonmetallic group, X is sulfur, selenium or telluriu'm, and R. is analiphatic radical, and where the TO- and ---CW groups are in the 1, 4positions relative to each other on a sixmembered carbon ring structure.In this class of compounds the metals selected for the preparation ofthe salts are from groups I, II, III, IV and VIII of the periodic tableand are preferably cobait, nickel, tin, zinc, aluminum, copper, sodium,potassium, calcium, magnesium, or barium. For many applications thealkaline earth metal salts are particularly preferred. Useful salts mayalso be formed from the nonmetallic basic groups, such as the oniumgroups. Thus T in the above formula may also represent ammonium,quaternary ammoniurm phosphonium, sulfonium or pyridonium groups and thelike. R. in the formula may represent any saturated aliphatic groupcontaining up to 20 carbon atoms and may be either straight or branched.If the additive is to be dissolved in a mineral oil, the group R shouldcontain at least two carbon atoms. In these compounds alkyl side chainsmay be attached to the nucleus, but such side chains are not ordinarilyrequired for oil solubility when the B group of the compound contains atless two carbon atoms.

It is intended that the above definition include also the sulfides ofthe various compounds, which may be formed by treating the compoundswith sulfurizing agents such as sulfur monochloride or dichloride orother sulfur halide. Generally, reaction with sulfur dichloride underproper conditions will give a monosulfide derivative, and reaction withsulfur monochloride will give a disulfide derivative. However, dependingupon ratios of reactants used, conditions of reaction and purity of thesulfur halides, a product whose sulfur content lies somewhere between amonosulfide and a disulflde may be obtained. Also, by suitable means itis possible to prepare polysulfides having up to four atoms of sulfur.Thus it is intended that the invention include compounds having thefollowing general structure:

where R is an alkyl radical, T is hydrogen or a metal equivalent ofhydrogen, the metal being selected from groups I, II, III, IV and VH1 ofthe periodic table, or a salt forming non-metallic group, and a: is inan integer, from 1 to 4. It should be understood that the group S; inthe, above formula is not necessarily intended to represent merelystraight chain sulfur linkages between the aryl groups, e. g. S', --SS-,S--SS, etc., but also other ypes such as and the like, as well as morethan one linkage o sulfur, as for example:

It should also be understood that the sulfurized ample, the ethyl esterof p-hyidroxy dithiobenzoic acid may be formed by reaction of phenetolwith carbon disulfide in the presence of aluminum chloride in accordancewith the method described by Jiirg (Ben, vol. 60': 1466 (1927)). Themetallic salts of these compounds are conveniently formed by reactionwith a metallic base, such as barium hydroxide. To obtain thecompoundsof the present invention may include sulfide polymers havingthree or more aromatic nuclei linked by sulfur atoms, as well asmixtures of monosulfides, disulfides, trisulfides, sulfide polymers andthe like. The sulfide compounds may be illustrated by the followingexamples:

Sulfide of the ethyl ester of p-hydroxy dithiobenzoic amd Sulfide of thebarium salt of the ethgl ester of p-hydroxy dithiobenzoic aci Asspecific examples of the compounds most preferred for use in accordancewith the present invention may be mentioned the ethyl ester of .bestyields, the water produced during the reaction should be removed asformed. The sulfides of either the hydroxy compound or its salt may beformed by reaction with a sulfurizing agent, such as sulfur monochlorideor dichloride.

Generally, when the additives of the present invention are incorporatedin lubricating oils new additives.

Exsuru 1 Ethyl ester of p-hudromu dithiobenzoic acid A three-way flaskequipped with a stirrer, a thermometer and a return condenser fittedwith a water trap was charged with grams of phenetol, grams ofdry carbondisulfide and approximately '75 grams of dry aluminum ch10- rlde. Allair vent lines were closed with calcium chloride drying tubes. Thereaction started at about 25 0., and the mixture was gradually heated toa final temperature of 70 to C. during a total heating period of livehours. No

" hydrogen chloride gas was evolved after four p-hydroxy dithiobenzoicacid, the barium salt I of the ethyl ester of p-hydroxy dithiobenzoicacid, the sulfide of the ethyl ester of p-hydroxy dithiobenzoic acid,the sulfide of the barium salt of the ethyl ester of p hydroxydithiobenzoic acid, the octyl ester of p-hydroxy dithiobenzoic acid, thebarium salt of the octyl ester of phydroxy dithiobenzoic acid, thesulfide of the ethyl ester of p-hydroxy dithiobenzoic acid, the

sulfide of the barium salt of the octyl :ester of p-hydroxydithiobenzoic acid, the cetyl ester of p-hydroxy dithiobenzoic acid, thezinc salt of the isododecyl ester of p-hydroxy dithiobenzoic acid, thedisulfide of the calcium salt of the amyl ester of p-hydroxydithiobenzoic acid, the sulfide of the tin salt of the octadecyl esterof p-hydroxy dithiobenzoic acid, and the wax alcohol ester of p-hydroxydithiobenzoic acid. 1

The hydroxy compounds used as such in accordance with the presentinvention or for preparing salts to be so used may be convenientlyprepared by reaction of an alkyl aryl ether with carbon disulfide in thepresence of a Friedel- Crafts catalyst, whereby rearrangement occurs toform a hydroxy group in place of the aroxy group, and a =csm group isformed in the para position to the hydroxy group. For ex?- hours. Thecrude product was removed from the flask and given'a quick wash withcold water to remove water soluble organic and inorganic materials. Thewater insoluble product, after drying, weighed 28.0 grams. The meltingpoint was approximately 50 to 57 C.

Exnlru 2 Barium salfo! the ethyl ester of p-hildromu dithiobenzoic acid5.grams of the product prepared as in Example 1 were added slowly to 250ml. of warm chloroform in a reaction vessel provided with a refluxcondenser. The ester went into solution slowly. To the warm chloroformsolution ri grams of Ba(OH)z.8HzO were slowly added. Water was liberatedfrom the reaction during this process. and was removed as formed bymeans of a water .trap attached to the condenser. After all of theBa(OH) 2.81120 had reacted, i. e., after about one hour, the chloroformand all other volatile materials were removed from the barium salt byevaporation. This salt was believed to have the following structure: e.

Analysis of the salt Theory Found Per cent Per cent 24. 7

EXAMPLE 3 Sulfide of the barium salt of the ethyl ester of p-hydrowydithiobenzoic acid the value of a: being substantially 2.

In the following examples various tests were applied to determine thevalue of the additives in compounded lubricating oils.

EXAMPLE 4 Corrosion test In order to determine the effect of the bariumsalt prepared as in Example 2 in preventing the corrosion of acopper-lead alloy when in contact with a blended oil containing thesame, 0.75% of the salt was dissolved in a refined mineral lubricatingoil of 63 seconds viscosity Saybolt at 210 F. and a viscosity index of40, and this blend was compared with an unblended sample of the samebase stock in a corrision test conducted as follows:

500 cc. of the oil to be tested were placed in a glass oxidation tube(13" long and-2% diameter) fitted at the bottom with a A" bore air inlettube perforated to facilitate air distribution. The oxidation tube wasimmersed in a heated bath so that the oil temperature was maintained at325 F. during the test. Two quarter sections of automotive bearings ofcopper-lead alloy of known weight having a total area of 25 sq. cm. wereattached to opposite sides of a stainless steel rod which was thenimmersed in the oil and rotated at 600 R. P. M., thus providingsufficient agitation of the sample during the test. Air was then blownthrough the oil at the rate of 2 cu. ft. per hour. To increase theseverity of the test, the hearings were washed and weighed at the end ofeach four hour period and then polished and reweighed before continuingfor another four-hour period. When submitted to this test the blendprepared as described above was found to cause a bearing weight loss of21 mg. in 16 hours, while the unblended base stock caused a loss of '62mg. in

only 4 hours.

Examm: 5

Corrosion test A blend consisting of 0.75% of the sulfurized barium saltprepared as described in Example 3 dissolved in a base oil of 52 secondsSaybolt viscosity at 210 F. and viscosity index of 104 was submitted tothe test described in Example 4, and

was found to cause a loss of weight of copperlead bearings amounting to28 mg. in 16 hours, while a sample of the blank base oil caused a lossof mg. in 4 hours.

EXAMPLE 6 Copper strip test To determine the staining tendency oflubricating oil blends containing new additives ,a test was appliedwhich consisted of a modification of the conventional A. S. T. M.corrosion test (Test- D -30) known as the copper strip test, withmodifications embodying the employment of 3 hour test periods at atemperature of 210 F. If the strip is not stained or if only a lightbrassy stain is shown, the oil is considered satisfactory. Oils whichproduce a definitely'brassy red, redbrown, blue or black stain aregenerally considered not satisfactory. This test was applied-to theblends of lubricating oil and additive prepared in Examples 4 and 5containing 0.75% of the barium salt and the sulfurized barium salt. Ineach case the copper strip showed only a slight red stain after a 3 hourtest, and the oil blends were considered satisfactory.

Exsmts '7 Carbon black dispersion test A carbon black dispersion testwas carried out to measure the comparative effectiveness of the bariumsalt described in Example 2 as an agent for dispersing sludge inlubricating oil. In this test 6% by Weight of activated carbon was addedto the oil blend containing the additive and thoroughly dispersed in theoil by stirring with an "egg beater type mixer for 15 minutes while thetemperature of the oil was maintained at 250 F. 250 cc. of the blend wasthen placed in a 250 cc. graduated ylinder and allowed to settle for 24hours while the temperature was maintained at 200 F. If an additive isnot a dispersing agent, the carbon black settles rapidly at this pointleaving clear oil at the top in an hour or two. A very effectivedisperser will maintain the carbon black in suspension so that no changein the opaque slurry is apparent even after a 24- hour period. With al1but the most potent dispensers stratification occurs with a black layerat the bottom (high concentration of carbon black) and a blue opaquelayer at the top (reduced carbon black concentration). Cases of thistype, known as "blue line separations, are only detectable in reflectedlight. The base oil used for the test was a solvent extractedMid-Continent oil of 52 seconds Saybolt viscosity at 210 F. The resultsof the test when applied to a blend containing 0.75% of the barium saltin the base oil showed no settling of the carbon black during the24-hour period. A similar test of the for example, by the polymerizationof olefins or by the reaction of oxides of carbon with hydro.

. gen or by the hydrogenation of coal or its products. In certaininstances cracking coil tar fractions and coal tar or shale oildistillates may also be used. Also, for special applications, animal,vegetable or fish oils or their hydrogenated or voltolized products maybe employed, either alone or in admixture with mineral oils.

For the best results the base stock chosen should normally be that oilwhich without the new additives present gives the optimum performance inthe-service contemplated. However, since one advantage of the additivesis that their use also makes feasible the employment of lesssatisfactory mineral oils or other oils, no strict rule can be laid downfor the choice of the base stock. Certainessentials must of course beobserved. The oil'must possess the viscosity and volatilitycharacteristics known to be required for the service contemplated. Theoil must be a satisfactory solvent for the additive, although in somecases auxiliary solvent agents may be'used.'

The'lubricating oils, however they may have been produced, may varyconsiderably in viscosity and other properties depending upon theparticular use for which they are desired, but they usually range fromabout 40 to 150 seconds Saybolt vis cosity at 210 F. For the lubricationof certain low and medium speed Diesel engines the gen eral practice hasoften been to use a'lubricating oil base stock prepared from naphthenicor aromatic crudes and having a Saybolt viscosity at 210 F. of 45 to 90seconds and a viscosity index of to 50. However, in certain types ofDiesel service, particularly with high speed Diesel engines, and ingasoline engine service, oils of higher viscosity index are oftenrequired, for exam- Dle up to 75 or 100, or even higher, viscosityindex.

In addition to the materials to be added according rtothe presentinvention the lubricating oils may also contain other agents, such asdyes, pour depressors, heat thickened fatty oils, sulfurized fatty oils,organo metallic compounds, metallic or other soaps, sludge dispersers,antioxidants, thickeners, viscosity index improvers, oiliness agents,resins, rubber, olefin polymers, voltolized fats, voltolized mineraloils, and/or voltolized waxes and colloidal solids such as graphite orzinc oxide, etc. Solvents and assisting agents, such as esters, ketones,alcohols, aldehydes, halogenated or nitrated compounds, and the like,may

octadecyl benzyl alcohol or mixtures of these various alcohols, whichmay be pure or substantially pure synthetic alcohols. One may also usemixed naturally occurring alcohols such as those found in wool fat(which is known to contain a substantial percentage of alcohols havingabout 16 to l8 carbon atoms) and in sperm oil (which contains a highpercentage of cetyl alcohol) and although it is preferable to isolatethe alcohols from those materials, for some purposes, the wool fat,sperm oil or other natural'products rich in alcohols may be used per se.Products prepared synthetically by chemical processes may also beused,'such as alcohols prepared by the oxidation of petroleumhydrocarbons, e. g., paraflin wax, petrolatum, etc.

The additives of the present invention will in some instances be usedadvantageously in lubrieating oils in conjunction with other detergentadditives such as metal soaps of fatty acids, metal naphthenates, metalphenates, metal mahogany.

sulfonates, metal phenol sulfonates, metal phenol sulfide salts and thelike. I

In addition to being employed in crankcase lubricants the additives ofthe present invention may also be used in extreme pressure lubricants,

general machinery oils, greases and rust preventive compositions. Theymay also be used in motor fuels, kerosene, paraffin waxes (particularlyhigh melting point waxes) and in high molecular weight polymerizedhydrocarbon products.

Among (the various high molecular weight polymerized hydrocarbonproducts in which the additives of the present invention may find useare natural rubber and various synthetic rubbers such as those preparedfrom butadiene, isoprene, isobutylene and copolymers of these with eachother and/or with other oleflnic materials. The function of theadditives in these compositions is that of inhibiting breakdown ordepolymerization of the polymers caused by the action of heat and/oroxidation either during use or'in storage. Also in some instances theyserve to inhibit breakdown caused merely by mechanical working. Theadditives may be used alone as the sole inhibitor in these rubber-likecompositions or they may be employed in conjunction with otherantioxidants,

vulcanization accelerators, and the like.

The new additives have been found to be par- .ticularly useful forpreventing the breakdown of the molecular weight of polymerizedisobutylene.

.A test showing the value of the additive in preventing'suchdeterioration is described in the following example.

Exmu 8- A polymerized isobutylene product suitablefor use as aninsulating material and as a plasticizer able are the higher alcoholshaving eight or more 5 carbon atoms and preferably 12 to' 20 carbonatoms. The alcohols may be saturated straight and branched .chainaliphatic alcohols such as octyl alcohol, CaHuOH, lauryl alcohol,C12H25OH,

cetyl alcohol, CraHaaOI-I, stearyl alcohol, sometimes referred to asoctadecyl alcohol, CmI-Ia-zOH. and the like; the corresponding olefinicalcohols such as oleyl alcohol; cyclic alcohols, such as naphthenicalcohols; and aryl substituted alkyl alcohols. for instance, phenyloctyl alcohol, or

for natural or synthetic rubber and having a molecular weight of about88,000, as determined by the Staudinger viscosity method, was blendedwith 0.25% of the ethyl ester of p-hydroxy dithiobenzoic acid by mixingwith the polymer one. laboratory rubber mill at 87 F. for 15 minutes,the roll clearance being 0.017". Ablank sample (polymer withoutvtheinhibitor) was alsomilled for 15 minutes at 87 F. (room temperature).The exact temperature of the polymer after milling was found to be F.The products were then placed in an oven at 300 F. for 24 hours. Anopening in one end of the oven allowed free access of the sample to airduring the heating period. After the samples had been heated theirnolecular weights were again determined. The results are as follows:

A prox. molecr wt. after 15 min. milling at room temperature Initialmolecr Sample ular weight Blank Polybutene +0.25%

inhibitor 74, 000

It will be seen from these results that the additive inhibited to aslight extent the depolymerization resulting from the milling operationand to a considerable extent the loss in molecular weight brought aboutby heating in the presence of air. g or Exmtn 9 A test similar to' thatdescribed in Example 8 was applied to samples of a synthetic rubberconsisting of a copolymerof isoprene and isobutylene (1.45% isoprene98.55% isobutylene) both with and without an inhibitor consisting of thebarium salt of the ethyl ester oiP-hydroxy dithiobenzoic acid, preparedas described in Example 2. The blended product contained 2% of thebarium salt. The results or the test are as follows:

than? A 1 Initial moleomo Sam is 15 min. milling er wt. alter p weightat room tem- 24km. at 300 F.

pemture opo er 0.02% to about 5% of a compound having the structure XTO.Ar. XB

where Ar is an aromatic nucleus, T is a salt forming entity selectedfrom the group consisting of hydrogen, a metal valence equivalent ofhydrogen, the metal being selected from groups I, II, III, IV and VIIIof the periodic table, and a nonmetallic basic group, X is a non-metalof group VI of the periodic table, and R is an aliphatic radical, andwhere the TO-- and -cm groups are in the 1,4 positions relative to eachother on a six membered carbon ring structure.

2. A mineral oil containing about 0.02% to about 5% of a compound havingthe structure X TQAn xll where Ar is an aromatic nucleus, T is a saltforming entity selected from the group consisting of hydrogen, a metalvalence equivalent of hydrogen, the metal being selected from groups I,II, III, IV and VIII of the periodic table, and a nonmetallic basicgroup, X is a non-metal of group VI of the periodic table, and R is analiphatic radical, and where the T0- and -cm groups are in the 1,4positions relative to each other on a six membered carbon ringstructure.

3. A lubricant comprising a major proportion of a mineral oil of thelubricating oil range and about 0.02% to about 5% of a compound of. theformula s=csn where R is an aliphatic radical and T is a salt formingentity selected from the group consisting of hydrogen, a metal valenceequivalent ofhydrogen, the metal being selected from groups I, II, III,IV and VIII of the periodic table, and a non-metallic basic group.

4. A lubricant comprising a. major proportion of a mineral oil of thelubricating oil range and about 0.02% to about 5% of a compound of theformula where T is a member of the group consisting of hydrogen and analkaline earth metal valence equivalent of hydrogen.

5. A lubricant comprising a majo proportion of a mineral oil of thelubricating oil range and about 0.02% to about 5% of the ethyl ester ofp-hydroxy dithiobenzoic acid.

6. A lubricant comprising a major proportion of a mineral oil of thelubricating 011 range and about 0.02% to about 5% of the barium salt ofan alhl ester of p-hydroxy dithiobenzoic acid.

7. A lubricant comprising a major proportion of a mineral oil of thelubricating oil range and about 0.02% to about 5% of the barium salt ofthe ethyl ester of p-hydroxy dithiobenzoic acid.

8. A material consisting essentially of non-gaseous aliphatichydrocarbons containing about 0.02% to about 5% of a member of the groupconlastin of reaction products of a sulfur halide with a compound or theformula s=osa H where R m an aliphatic radical, and salts of suchreaction products selected irom the group consisting of metal saltsderived from metals of groups I, II, 111, IV and vm of the periodictable and salts formed from non-metallic basic radicals.

9. A lubricant comprising a major proportion of a mineral oil of thelubricating oil range and about 0.02% to about 5% oi a compound havingthe structure where R is an alkyl radical, T is a salt forming entityselected from the group consisting of hydrogen, a metal valenceequivalent of hydrogen, the metal being selected from groups I, H,

I1I, IVand' of the periodic table; and a non-metallic basic group, and xis an integer, from 1 to 4. v

10. A lubricant comprising a major proportion of a mineral 011 oi thelubricating oil range and about 0.02% to about 5% of aco'mpound havingthe structure where M is an alkaline earth metal.

1 1. A lubricant comprising a major proportion of a mineral oil 01' thelubricating oil range and ToJmtxB where Ar is an aromatic nucleus, T isa member of the group consisting of hydrogen, a metal valence equivalentof hydrogen, the metal being selected from groups I, II, III, IV andVIII of the periodic table, and-Ma non-metallic basic group,

X is a non-metal 01' group VI of the periodic table,

and R is an aliphatic radical, and where the TO- and CXXR. group groupsare in the 1, 4 8 positions relative to each other on a six memberedcarbon ring structure.

13. A normally solid high molecular weight aliphatic hydrocarbonpolymeric material containing about 0.1% to about 5% of a compound ofthestructure where R. is an aliphatic radical and 'I is a salt formingentity selected from the group consisting of hydrogen, a metal valenceequivalent 0! hydrogen, the metal being selected from groups I, II, III,IV and V111 of the periodic table, and a non-metallic basic group.

14. A high molecular weight polybutene con- 25 taining about 0.1% toabout 5% of the ethyl ester of p-hydroxy dithlobenzoic acid.

15. A high molecular weight rubber-like co-, polymer of isobutylene andisoprene containingabout 0.1 to about 5% of the barium salt 01 the ethylester of p-hydroiw dithiobenzoic acid.

DAVID W. YOUNG.

